After you click the File tab, you can see the Microsoft Office Backstage view. The Office Backstage view is where you manage your files and the data about them — creating, saving, inspecting for hidden metadata or personal information, and setting options. In short, it is everything that you do to a file that you don't do in the file.
The File tab in Microsoft Office 2010 replaces the Microsoft Office Button and File menu used in earlier releases of Microsoft Office.
What do you want to know?
Where is the File tab located?
The File tab is the colored tab, for example, the blue tab in Microsoft Word 2010, located in the upper-left corner of Microsoft Office 2010 programs.
What do I see when I click the File tab?
When you click the File tab, you see many of the same basic commands that you saw when you clicked the Microsoft Office Button or on the File menu in earlier releases of Microsoft Office, such as Open, Save, and Print.
Show me Backstage view
You can watch a video that shows you more about Backstage view at Video: What and where is Backstage view.